RTM angle gathers using Poynting vectors

Abstract

Angle-domain common image gathers have been shown to provide several advantages for the analysis of migrated images. In this abstract we describe an efficient new method for creating angle gathers for reverse time migration (RTM). The method relies on the computation of the direction of energy flux (known in electromagnetics as the Poynting vector) in the space-time domain. Given the Poynting vectors for source and receiver wavefields, we may readily derive reflection angle and azimuth, and reflector dip and azimuth if desired. Unlike some previously considered angle-gather algorithms, the method depends only on local information at the reflection point, thereby avoiding the loss of resolution inherent in mixing quantities from different horizontal locations. In addition, we derive the weight function needed to produce correct relative amplitudes for these angle gathers.